Twin-spindle CNC machining centers (see, e.g., prospectus: Huller Hille, nb-twin) with automatic tool changer, in which one or two tool magazine disks rotatable around a central horizontal axis are arranged on the side next to the working spindles, belong to the state of the art. The axis of rotation of these tool magazine disks is arranged in parallel to the longitudinal axis of the working spindles (spindle axis). Recesses for receiving the tools, whose longitudinal axes likewise extend in parallel to the axis of rotation of the tool magazine disks and of the working spindle, are arranged at the outer circumference of the tool magazine disks. These prior-art tool magazine disks require a relatively large space and can receive only a limited number of tools.
A machine tool with a plurality of spindles for the simultaneous or different, separate machining of a plurality of works, in which at least two spindles that can be driven around their axes of rotation are displaceable at least in their longitudinal axis (direction C) and in a direction at right angles thereto (direction X), has been known from DE 195 14 058 A1. A common multiple turret, which is tipped with tools associated with both tool spindles, is associated with the vertically arranged spindles. The tool turret comprises an essentially circular disk, on the circumference of which the tools are arranged with their tips to the outside. The tool turret is rotatable around an axis that is slightly tilted in relation to the horizontal direction. Only relatively few tools can be arranged on the tool turret in this case as well.